Patent application title: Timing control system for pulse detonation engines

Abstract:

An engine timing input system is described for pulse detonation engines
that allows for accurate engine timing when rotary or cylindrical valves
are used to distribute an air/fuel mixture for combustion. The invention
uses a profile disk having a predetermined circumferential edge
corresponding to valve position to provide for accurate engine timing. A
frequency wheel is used in conjunction with the profile disk to provide a
more accurate representation of valve position by partitioning the valve
position into multiple pulses during each rotation of the rotary or
cylindrical valve. The profile disk and frequency wheel when used with
programmable timing circuitry signal fuel valve timing and ignition
relative to the rotating valve.

Claims:

1. An engine timing input system comprising:a profile disk having a center
and a circumferential edge;said profile disk center coupled to a rotating
member of the engine wherein one revolution of said rotating member
represents one engine cycle; anda profile disk sensor positioned in
proximity to said profile disk edge, wherein said profile disk sensor
translates said circumferential edge into a profile disk signal for
output.

2. The system according to claim 1 wherein said profile disk
circumferential edge is not at a constant radius from said center.

3. The system according to claim 2 wherein said profile disk
circumferential edge further comprises having at least one step.

4. The system according to claim 3 wherein said step is indexed with a
predetermined position of the engine.

5. The system according to claim 4 further comprising a profile disk
signal conditioner coupled to said profile disk sensor output wherein
said signal conditioner processes said profile disk sensor signal into a
predefined pulse train.

6. The system according to claim 5 wherein said profile disk signal
conditioner comprises:a voltage comparator coupled to said profile disk
sensor output wherein said voltage comparator shapes said profile disk
output into a pulse train for output; anda one shot coupled to said
voltage comparator output wherein said one shot modifies said voltage
comparator pulse train pulse width.

7. The system of claim 6 further comprising:a frequency wheel having a
center and a circumferential edge having a plurality of slots;said
frequency wheel center coupled to said rotating member of the engine;
anda frequency wheel sensor positioned in proximity to said frequency
wheel edge, wherein said sensor translates said circumferential edge into
a frequency wheel signal for output.

8. The system of claim 7 further comprising a frequency wheel signal
conditioner coupled to said frequency wheel sensor output wherein said
frequency wheel signal conditioner processes said sensor signal into a
predefined pulse train.

9. The system according to claim 8 wherein said frequency wheel signal
conditioner comprises a voltage comparator coupled to said frequency
wheel sensor output wherein said voltage comparator shapes said frequency
wheel output into a pulse train for output.

10. The system according to claim 9 wherein said at least one step of said
profile disk is indexed with one slot of said frequency wheel.

11. The system of claim 10 wherein said slots in said frequency wheel
correspond to angular degrees of engine position.

12. The system according to claim 11 wherein said profile disk pulse train
in conjunction with said frequency wheel pulse train determines engine
timing position.

13. The system according to claim 12 wherein the engine is a pulse
detonation engine.

14. The system according to claim 13 wherein said profile disk sensor is a
Hall-effect device.

15. The system according to claim 14 wherein said frequency wheel sensor
is a Hall-effect device.

16. An engine timing input' system comprising:a profile disk having a
center and a circumferential edge;said profile disk center coupled to a
rotating member of the engine wherein one revolution of said rotating
member represents one engine cycle;a profile disk sensor positioned in
proximity to said profile disk edge, wherein said profile disk sensor
translates said circumferential edge into a profile disk signal for
output;a frequency wheel having a center and a circumferential edge;said
frequency wheel center coupled to said rotating member of the engine;
anda frequency wheel sensor positioned in proximity to said frequency
wheel edge, wherein said sensor translates said circumferential edge into
a frequency wheel signal for output.

17. The system of claim 16 further comprising a profile disk signal
conditioner coupled to said profile disk sensor output wherein said
signal conditioner processes said sensor signal into a predefined pulse
train and a frequency wheel signal conditioner coupled to said frequency
wheel sensor output wherein said frequency wheel signal conditioner
processes said sensor signal into a predefined pulse train.

18. The system according to claim 17 wherein said profile disk
circumferential edge further comprises having at least one step.

19. The system according to claim 18 wherein said profile disk signal
conditioner further comprises:a voltage comparator coupled to said
profile disk sensor output wherein said voltage comparator shapes said
profile disk output into a pulse train; anda one shot coupled to an
output of said voltage comparator wherein said one shot modifies said
voltage comparator pulse train pulse width.

20. The system of claim 19 further comprising a frequency wheel signal
conditioner coupled to said frequency wheel sensor output wherein said
frequency wheel signal conditioner processes said sensor signal into a
predefined pulse train.

21. The system of claim 20 wherein said frequency wheel circumferential
edge has a plurality of slots.

22. The system according to claim 21 wherein said at least one step of
said profile disk is indexed with one slot of said frequency wheel.

23. The system of claim 22 wherein said slots in said frequency wheel
correspond to angular degrees of engine position.

Description:

BACKGROUND OF THE INVENTION

[0001]The invention relates generally to the field of intermittent
combustion engines. More specifically, embodiments of the invention
relate to system's for controlling detonation combustor timing input for
pulse detonation engines.

[0002]A pulse detonation engine (PDE) is a type of intermittent combustion
engine that is designed primarily to be used in high-speed, high-altitude
environments. The PDE can achieve an efficiency far surpassing gas
turbines with almost no moving parts.

[0003]Like other jet engines, the PDE takes in air at its front end. In a
conventional jet engine, intake air would be driven by a fan through a
multistage compressor and into a combustion section or burner where fuel
would be burned continuously.

[0004]While the operating principle of a PDE is similar to a pulse jet
engine, the fundamental difference of a PDE is that it detonates the
air/fuel mixture. The pulse jet uses a series of shutters, or careful
tuning of the inlet, to force the air to travel only in one direction
through the engine to ensure that the mixture exits to the rear thereby
pushing an aircraft forward. Another difference is the way in which
airflow and combustion in the engine is controlled.

[0005]Typically, fuel is consumed either by deflagration, which is slow
burning, or detonation, which is a more energetic process. Detonation is
inherently more efficient than deflagration. The PDE combustion process
burns all of its air/fuel mixture while still inside the engine at a
constant volume. While the maximum energy efficiency of most types of jet
engines is approximately 30%, a PDE can attain an efficiency near 50%.

[0006]All regular jet engines and most rocket engines operate on the
rapid, but subsonic combustion of fuel. The PDE is a jet engine that
operates on the supersonic detonation of fuel.

[0007]One attribute of deflagration is that the flame travels at a speed
significantly lower than the speed of sound. However, detonation is a
more powerful reaction of the air/fuel mixture and results in such a
rapid reaction that the pressure wave created travels at supersonic
speeds. Detonation is a violent explosion and produces higher pressures
than the process of deflagration.

[0008]If a tube were closed at one end and filled with a mixture of air
and fuel at the closed end and ignited by a spark, a combustion reaction
would propagate down the tube. In deflagration, the reaction would move
at tens of meters per second. In detonation, a supersonic shock wave
travels the length of the tube at thousands of meters per second.
Detonation compresses and ignites the air/fuel mixture almost
instantaneously in a narrow, high-pressure heat-release zone.

[0009]To create a narrow, high-pressure heat-release zone, the engine must
precisely coordinate fuel input, airflow and ignition to create a
deflagration-to-detonation transition (DDT). DDT is the process by which
an ordinary flame suddenly accelerates into a powerful detonation. While
detonation generates more thrust than deflagration for the same fuel
consumption, only tiny amounts of fuel can be detonated at a time. For a
continuous thrust, many detonations per second are required. For example,
the cycle rate of a pulse jet is typically 250 pulses per second. A PDE
is thousands of pulses per second.

[0010]For a realizable PDE, an air/fuel flow is typically switched between
a plurality of combustor tubes, where in each, the air/fuel mixture must
detonate cleanly many times per second. The switching is performed using
a rotary or cylindrical valve spinning at thousands of revolutions per
minute having apertures which alternately open and block airflow to an
inlet for each combustor.

[0011]A cycle is formed in which the valve admits fuel into a stream of
air flowing into a combustor and a spark initiates a DDT producing a
shock wave that travels the length of the combustor generating thrust.

[0012]PDE designs that use rotary valves to control detonation require a
sophisticated synchronization system to ensure that the externally driven
valve opens and closes each combustor to inject and detonate the charge
at exactly the right moment to optimize detonation of the air/fuel
mixture. Detonating the mixture either too early reduces combustion
efficiency and if late, the mixture will leave the combustor tube.

[0013]The position of the rotary or cylindrical valve is important for the
timing of air/fuel mixture and subsequent ignition. One misfire (fuel or
ignition at an inappropriate time) can destroy the entire engine. It is
therefore desired to have a ±0.5 degree of angular resolution accuracy
for the valve when performing ignition timing.

SUMMARY OF THE INVENTION

[0014]Although there are various systems and methods that perform timing
control for pulse detonation engines, such systems and methods are not
completely satisfactory. The inventor has discovered that it would be
desirable to have a system that allows for accurate engine timing when
rotary or cylindrical valves are used to distribute an air/fuel mixture
for combustion at either subsonic or supersonic speeds.

[0015]The invention uses a profile disk having a predetermined
circumferential edge corresponding to valve position to provide for
accurate engine timing. A frequency wheel is used in conjunction with the
profile disk to provide a more accurate representation of valve position
by partitioning the valve position into multiple pulses during each
rotation of the rotary or cylindrical valve. The profile disk and
frequency wheel when used with programmable timing circuitry signal fuel
valve timing and ignition relative to the rotating air valve system. The
control system may be slaved off of valve position.

[0016]Another aspect of the invention is an engine timing input system.
Systems according to this aspect of the invention comprise a profile disk
having a center and a circumferential edge, the profile disk center
coupled to a rotating member of the engine wherein one revolution of the
rotating member represents one engine cycle, and a sensor positioned in
proximity to the profile disk edge wherein the sensor translates the
circumferential edge into a signal for output.

[0017]Yet another aspect of the system is a signal conditioner coupled to
the sensor output wherein the signal conditioner processes the sensor
signal into a predefined pulse train.

[0018]The details of one or more embodiments of the invention are set
forth in the accompanying drawings and the description below. Other
features, objects, and advantages of the invention will be apparent from
the description and drawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019]FIG. 1 is an exemplary cross-sectional view of a pulse detonation
engine.

[0020]FIG. 2A is an exemplary top view of a rotary valve disk.

[0021]FIG. 2B is an exemplary side view of the rotary valve disk shown in
FIG. 2A.

[0022]FIG. 3A is an exemplary top view of the fuel manifold inlets in
relation to the rotary valve disk.

[0023]FIG. 3B is an exemplary top view of the air manifold inlets in
relation to the rotary valve disk.

[0024]FIG. 4 is an exemplary schematic diagram of the engine timing input
according to the invention.

[0025]FIG. 5 is an exemplary top view of the profile disk.

[0026]FIG. 6A is an exemplary plot of the profile disk position sensor
output voltage Vsensor1--.sub.out over time.

[0032]Embodiments of the invention will be described with reference to the
accompanying drawing figures wherein like numbers represent like elements
throughout. Further, it is to be understood that the phraseology and
terminology used herein is for the purpose of description and should not
be regarded as limiting. The use of "including," "comprising," or
"having" and variations thereof herein is meant to encompass the items
listed thereafter and equivalents thereof as well as additional items.
The terms "mounted," "connected," and "coupled" are used broadly and
encompass both direct and indirect mounting, connecting, and coupling.
Further, "connected" and "coupled" are not restricted to physical or
mechanical connections or couplings.

[0033]Embodiments of the invention provide systems for controlling jet
engine timing based upon the position of a rotary or cylindrical air/fuel
mixture inlet valve. The invention provides an engine timing input using
a sensor and a profile disk as the primary element that coordinates
cyclical engine function position with other functions. A frequency wheel
provides for a more accurate representation of valve position by
partitioning the valve position as indexed by the profile disk into
multiple pulses for each engine cycle. An accuracy of at least ±0.5
degrees may be achieved. In one embodiment, the invention is deployed as
an engine timing input system for a PDE.

[0034]Shown in FIG. 1 is a cross-sectional view of an embodiment of a PDE
to illustrate the timing control system of the invention. The PDE has at
least one combustor (detonation chamber) 105 having an elongated tubular
construction. If more than one combustor 105 is used, the lengths of the
combustors 105 extend parallel to each other to produce thrust in the
same direction, or the combustors may be combined or extended in
different directions to produce a cumulative parallel thrust. A nozzle
110 may be employed at the outlet ends of the combustors 105 to unify
thrust. The exemplary embodiment uses a cluster of four combustors 105.

[0035]The combustors 105 are fed an air/fuel mixture with air from an
inlet air manifold 115 and fuel from a fuel manifold 120. The inlet for
the air manifold 115 may be in the form of an inlet shock cone. The fuel
manifold 120 delivers fuel from a fuel source 125 which can be controlled
by a fuel valve 130. The PDE may use solid, liquid or gas fuel 125.

[0036]The combustors 105 are coupled to the inlet air 115 and fuel 120
manifolds by an intake manifold/rotary valve assembly 135. The intake
manifold/rotary valve assembly 135 has a rotary disk valve 140 positioned
between an intake manifold mounting plate 145 on an upper side of the
intake manifold/rotary valve assembly 135 and a combustor mounting plate
150 on a lower side. The intake manifold mounting plate 145 is coupled to
the inlet air 115 and fuel 120 manifolds. The combustor mounting plate
150 is coupled to the combustors 105.

[0037]The rotary disk valve 140 is rotatably mounted between the intake
manifold mounting plate 145 and combustor mounting plate 150. The rotary
disk valve 140 has at least one fueling aperture or port 200 as shown in
FIG. 2A and is rotated by a drive motor 155.

[0038]A timing profile disk 160 is coupled via a key or spline to a common
or auxiliary shaft of the drive motor 155. Mounted adjacent to the
profile disk is a sensor 165 for translating the position of the profile
disk 160. A frequency wheel 170 having a plurality of slots 180 located
in its outer periphery is coupled similarly, via a key or spline to a
common or auxiliary shaft of the drive motor 155. Mounted adjacent to the
frequency wheel is a sensor 175.

[0039]The rotation of the valve disk 140 opens and closes passages between
the intake manifold 145 and combustor 150 mounting plates. An igniter 185
positioned near an inlet end of each combustor 105 is used for ignition
and may be, for example, an electrode, a spark plug, an arc gap, or
other.

[0040]The rotary disk valve 140 has two fueling port openings 200 as shown
in FIGS. 2A and 2B. However, the number of ports may vary depending on
the number of combustors employed. The openings 200 are arranged
circumferentially around the center of the rotary valve disk 140 such
that as the disk valve 140 rotates, the openings 200 are selectively
positioned above the inlet ends of the combustors 105 for fueling. The
distance of the openings 200 from the center of the rotary disk valve 140
corresponds to the distance of the combustor 105 inlets from the central
axis of the combustor cluster.

[0041]The apertures 200 are arcuate in shape, defined by inner and outer
concentric edges. The distance between the inner and outer edges
(aperture width) of the openings 200 may be in matching correspondence
with the combustor 105 inlet openings.

[0042]Solid portions 205 are arranged between the openings 200 of the
rotary disk valve 140. As the rotary disk valve 140 rotates, the openings
200 and solid portions 205 are alternately positioned above the combustor
105 inlets. Therefore, fueling of a combustor 105 occurs when an opening
200 is positioned over an inlet end. A combustor may be fired when a
solid portion 205 is positioned over the same inlet end.

[0043]FIGS. 3A and 3B show top views of the fuel 120 and inlet air 115
manifolds, respectively. Fuel is distributed from the fuel source 125 to
each combustor 105 through individual fuel ducts 300. Each individual
fuel duct 300 has a finger-shaped cross-section and ends at a
finger-shaped port 305 which opens into the corresponding combustor 105.

[0044]The individual fuel ducts 300 are arranged partially within
individual air ducts 310 as shown in FIG. 3B. The individual air ducts
310 distribute air from the inlet air manifold 115 to the combustors 105.
Each individual air duct 310 ends in a circular air port 315 which opens
into the corresponding combustor 105. The finger-shaped fuel ports 305
(shown in phantom in FIG. 2B) are arranged within the air ports 315. It
will be appreciated that this arrangement allows each combustor 105 to be
topped off with air after it is fueled.

[0045]Having described the various components, the operation of the PDE of
FIG. 1 is as follows. Fuel is distributed from the fuel source 125 in a
steady mode, and air enters the inlet air duct manifold 115 also in a
steady mode. Rotary valve drive motor 155 rotates the rotary disk valve
140 between the fuel/air manifold mounting plate 145 and the lower
mounting plate 150.

[0046]In the fueling arrangement shown in FIGS. 3A and 3B, as an opening
200 of the rotary valve 140 moves into position over the inlet end of a
combustor 105, air and fuel enter that combustor through the
corresponding port 310, 305. As the rotary disk valve 140 continues to
rotate, the trailing edge of the opening 200 closes off the finger-shaped
fuel port 305, while air continues to enter the combustor 105 through a
portion of the circular port 315 which remains open. The air/fuel mixture
in the combustor 105 is topped off with air and any gaps that may exist
in the system are filled with air. The air acts as an additional
insulation buffer to protect the rotor assembly and prevent pre-ignition
of neighboring combustors 105.

[0047]Upon detonation, pressure forces will act upon all inner surfaces of
the combustors 105. The pressure differential from the inlet end to the
outlet end of each combustor 105, acting upon the rotary valve 140, will
contribute to the thrust of the vehicle. The combustors 105 may be
tapered so that pressure along the lateral inner surfaces of the
combustors will contribute to thrust. The transfer of the pressure forces
from the rotary valve 140 to the vehicle structure occurs through the
rotary valve bearings (not shown).

[0048]Engine thrust may be controlled by varying ignition timing, valve
rotation rate and fuel injection rate, for example, using a processor in
conjunction with an air/fuel-ignition algorithm. The operation of a PDE
may be controlled by software using a processor and inputs/outputs (I/O).
Signals input from the profile disk 165 and frequency wheel 175 timing
wheel may be connected to a sixteen bit counter/timer for generating
output pulses.

[0049]While one or more combustors 105 are fired, another one or more
combustors 105 are being fueled with an air/fuel mixture. For the four
combustor 105 PDE shown in FIG. 1, combustors 1 and 3 may fire while
combustors 2 and 4 are being fueled. As the rotary valve disk 140 seals
one or more combustors 105 for detonation, it opens adjacent combustors
105 for recharging.

[0050]The detonation cycle of the PDE combustors 105 can be described
according to the fundamental processes that occur within the combustors
105. The pulse detonation combustor cycle is comprised of several
distinct processes: 1) the detonation chamber is charged with an air/fuel
mixture, 2) the rotary valve 140 seals the fueled combustor 105 and
detonation is initiated at the closed end, 3) a detonation wave travels
through the combustor 105, 4) the detonation wave exits and burned gases
are exhausted, and 5) the rotary valve 140 opens the combustor 105 and
the combustor 105 is recharged while adjacent combustors 105 are
detonated.

[0051]Shown in FIG. 4 is the engine timing input system 400 of the
invention. The timing input system 400 provides ignition and fuel timing
for a PDE.

[0052]The timing input 400 comprises the profile timing disk 160 which has
a predetermined circumferential edge profile 405 and a frequency wheel
170 having a plurality of slots 180 located in its outer periphery. The
edge profile 405 has one or more elliptical cuts corresponding to the
number of combustors 105 employed in a particular PDE design.

[0053]The profile disk 160 embodiment shown in FIG. 5 has two elliptical
cuts and may therefore be configured for a PDE design that has two
combustors 105. The disk 160 may be coupled to the shaft of the rotary
valve 140, the shaft 410 of the rotary valve 140 drive motor 155, or
located on a geared or non-geared auxiliary shaft positioned away from
the rotary valve 140 (not shown).

[0054]Located adjacent and in proximity to the edge of the profile disk
160 is the non-contact sensor 165. The sensor 165 may be a magnetic field
sensor such as a Hall-effect device. The sensor 165 measures only one
component of a magnetic field. The edge profile 405 is translated by the
sensor 165 into an analog bipolar output voltage
Vsensor1--.sub.out.

[0055]The voltage magnitude of the sensor output signal
Vsensor1--.sub.out follows the change in magnetic flux produced
by the edge profile over time. The signal increases in amplitude as the
angular velocity of the profile disk 160 increases. The sensor output
Vsensor1--.sub.out is shown over time in FIG. 6A.

[0056]The timing input 400 produces a square wave pulse from the sharp
rising edge of the analog signal which corresponds to a specific angular
displacement of the rotary valve 140. The sensor 165 output
Vsensor1--.sub.out coupled to an op amp (operational amplifier)
IC1 such as a Motorola MC4741CL which is configured as a voltage
comparator. The comparator is clamped with a diode D1.

[0057]The comparator provides an output voltage VIC1--.sub.out
that equals 0 Vdc when the input voltage is greater than a predefined
reference voltage Vref. For this embodiment, Vref=0.354 Vdc.

[0058]When the input voltage Vsensor1--.sub.out is Less than the
reference voltage Vref, the comparator outputs a saturation voltage
VIC1--.sub.out=+Vsat. The operational amplifier is sourced
with ±15 Vdc causing the saturation voltage +Vsat to therefore be
+15 Vdc. The comparator output waveform VIC1--.sub.out is
reduced to +5 Vdc using a voltage divider comprising resistors R1
and R2,

[0059]where Vvd1 is the voltage measured across R2 and
Rload1. Rload1 is the input impedance of a coupled load. The
values for R1 and R2 can be set at 35.6 kΩ and 17.8
kΩ respectively. The voltage divider output Vvd1 is shown over
time in FIG. 6B.

[0060]The coupled load Rload1 is the input impedance of a monostable
multivibrator IC2, more commonly known as a one shot, such as a 74C221
IC. The one shot IC2 conditions the voltage divider output Vvd1 into
a pulse train having a predetermined amplitude and pulse width regardless
of the rotary valve 140 velocity. The one shot IC2 triggers on a trailing
or falling edge of the voltage divider output waveform Vvd1. A 150
μs pulse is generated by the one shot IC2. An external resistor
R3 and capacitor C1 define the pulse width and amplitude. The
values for the exemplary embodiment are 1.343 kΩ and 1.0 μF
respectively. The one shot IC2 output Vmm--.sub.out is shown
over time in FIG. 6c.

[0061]The one shot output Vmm--.sub.out is coupled to an engine
management system for the PDE (not shown). The management system
typically controls an ignition system of a high-tension design for
producing a spark across a gap. For example, the one shot output
Vmm--.sub.out may be coupled to a counter/timer digital
input/output (I/O) board, such as a National Instruments PC-TIO-10. A
discussion of the management system is beyond the scope of this
disclosure.

[0062]The frequency wheel 170 embodiment shown in FIG. 7 has 36 slots in
its outer periphery. The wheel 170 may be similarly coupled to the shaft
of the rotary valve 140, the shaft 410 of the rotary valve 140 drive
motor 155, or located on a geared or non-geared auxiliary shaft
positioned away from the rotary valve 140 (not shown).

[0063]Similar to the profile wheel 160 circuit, the frequency wheel 170
creates a change in magnetic flux. Located adjacent and in proximity to
the edge of the frequency wheel 170 is the non-contact sensor 175. The
sensor 175 may be a magnetic field sensor such as a Hall-effect device.
Unlike the profile disk 160, the frequency wheel 170 is divided into
thirty six slots 180 each having an angular displacement of ten degrees.
The rotation of the frequency wheel 170 creates an analog signal output
Vsensor2--.sub.out corresponding to each ten degrees of rotary
valve 140 angular displacement. The frequency wheel 170 analog output
signal Vsensor2--.sub.out combined with the profile disk 160
allows for accurate engine timing input for fuel and ignition timing and
control.

[0064]The change in magnetic flux produces a signal
Vsensor2--.sub.out that increases in amplitude as the angular
velocity of the frequency wheel 170 increases. The sensor 175 output, is
shown over time in FIG. 8A. The signal Vsensor2--.sub.out is
coupled to an operational amplifier IC3 such as a Motorola MC4741C1 which
is configured as a voltage comparator with a reference voltage of
Vref=0.354 Vdc. The comparator output VIC3--.sub.out is
clamped with a diode D2.

[0065]The comparator provides an output voltage VIC3--.sub.out
that equals 0 Vdc when the input voltage is greater than the predefined
reference voltage Vref.

[0066]When the input voltage Vsensor2--.sub.out is less than the
reference voltage Vref, the comparator outputs a saturation voltage
VIC3--.sub.out=+Vsat. The operational amplifier is sourced
with ±15 Vdc causing the saturation voltage +Vsat to therefore be
+15 Vdc. The comparator output waveform is reduced to +5 Vdc using a
voltage divider comprised of resistors R4 and R5,

[0067]where Vvd2 is the voltage measured across R5 and
Rload2. Rload2 is the input impedance of a coupled load. The
values for R4 and R5 can be set at 35.6 kΩ and 17.8
kΩ respectively. The voltage divider output Vvd2 is shown over
time in FIG. 8B.

[0068]Vvd2 may be coupled to a pulse detonation engine control
system.

[0069]Electric power for the rotary valve 140 drive motor 155, engine
management system, spark ignition system, and other electrical loads can
be derived from several sources including batteries, inlet air or gas ac
alternators/DC generators, electric turbo generators, or a combination of
these sources. Inlet air or gas generator systems consist of a turbine
rotor, placed in either the air or gas generator flow, in order to drive
a small electric generator.

[0070]The choice of ignition method is dependent on engine size and on the
characteristics of the fuel used.

[0071]Although the invention herein has been described with reference to
particular embodiments, it is to be understood that these embodiments are
merely illustrative of the principles and applications of the present
invention. It is therefore to be understood that numerous modifications
may be made to the illustrative embodiments and that other arrangements
may be devised without departing from the spirit and scope of the present
invention as defined by the appended claims.